This specification covers the chemical and mechanical requirements for stainless steel metric hexagon socket button (SBHCS) and flat countersunk (SFHCS) head cap screws with nominal thread M 3 through M 20 intended for use in applications requiring general corrosion resistance. These steels are designated into three classes: Austenitic Class A 1-50 in an annealed condition, Austenitic Class A1-55 in a cold worked condition, and Austenitic Class A 1-70 in a cold worked condition. The austenitic stainless steel socket screw shall be designated F879M A1-50, F879M A1–55, or F 879M A1-70. Screws shall be formed by upsetting or extruding, or both. Also, these screws shall be roll threaded. Austenitic alloys ClassA 1-50 screws, following manufacture, shall be annealed by heating to a certain temperature to obtain maximum corrosion resistance and minimum permeability. The screws shall be held for a sufficient time at temperature, then cooled at a rate sufficient to prevent precipitation of the carbide and provide the properties specified. Different tests shall be conducted in order to determine the following mechanical properties of screws: tensile strength, minimum extension, yield strength, elongation, Vickers hardness, and Rockwell hardness.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

1. Scope

1.1 This specification covers the chemical and mechanical requirements for stainless steel inch hexagon socket button (SBHCS) and flat countersunk (SFHCS) head cap screws with nominal thread 0.060 through 0.625 in. intended for use in applications requiring general corrosion resistance.

1.2 Two groups of austenitic stainless steel alloys and three conditions are covered. See Table 1 and Table 2.

(A)Actual full-size testing of condition CW and CW1 may result in decreased tensile strength because of the head configuration (see Table 3). For fasteners with nominal thread diameters larger than 0.625 in., the mechanical properties shall be agreed upon between the user and manufacturer.

(B)Core hardness is only required when full-size product testing cannot be accomplished.

(C)D denotes nominal thread size.

(A)304J3 from JIS G 4309.

1.3Units—The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

1.4The following precautionary caveat pertains only to the test method portion, Section 12, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

B18.3 Socket Cap, Shoulder and Set Screws (Inch Series) Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Two Park Ave., New York, NY 10016-5990, http://www.asme.org.

ICS Code

ICS Number Code 21.060.10 (Bolts, screws, studs)

Referencing This Standard

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